The invention relates to a travelling grate chain comprising chain links articulately connected together by grate pins, and support bodies which are disposed between the chain links, serve to receive the material to be treated and comprise slots for the passage of treatment gas.
Travelling grate chains of the aforementioned type are used primarily in travelling grates in which material to be treated is spread in a layer on the travellng grate chain and conveyed through at least one treatment chamber in which by means of gas the material is for example preheated, fired or cooled; the material to be treated is disposed on the top surface of the upper chain run and is discharged from the support surface of the travelling grate chain in the region of a deflection point at which the upper chain is deflected downwardly.
In known embodiments of a travelling grate chain the support bodies are generally formed by a support plate or grate plate in which a plurallity of grate slots are provided, and are generally disposed as integral parts between adjacent chain links, the top surfaces of the support or grate plates lying at the same level as the top surfaces or top edges of the chain links.
As a result of the complicated form of these grate plates serving as support bodies for the material to be treated, in some cases very great temperature differentials occur, giving rise to high thermal stresses within a grate plate, leading inevitably to many fractures and frequent destruction of grate plates. This effect is moreover intensified by the fact that the grate chain and thus also the grate plates are exposed in most cases during their travel to considerably higher temperatures in the region of the upper run than they are in the region of the lower run, where in many cases the grate chains are strongly cooled. These high thermal stresses frequently lead to damage both of the grate plates and of the chain links, and consequently undesirable shutdown times are necessary for the repair of the travelling grate chain. In addition, frequently a web between two adjacent grate slots in a grate plate breaks away, making it necessary to replace the entire grate plate. Since the grate plates serving as support bodies and to some extent also the chain links themselves are complicated parts, made as castings, the production of these parts is relatively expensive.